Laser speckle contrast imaging may accurately monitor anterior segment perfusion during strabismus surgery

Strabismus surgery is a common eye muscle surgery to treat strabismus or simply crossed eyes. This procedure helps in tightening or loosening eye muscles and aligns the position of the eyes so they're centered and can work together.

However the eye surgery is known to cause a dreaded complication of anterior segment ischaemia (ASI), caused by damage to the anterior ciliary arteries. To avoid ASI, a maximum of two rectus muscles are operated on at a time. Till date there is no method available for perioperative, real-time perfusion measurements during ocular muscle surgery.

A new study in BMJ Opthalmology aimed to investigate whether laser speckle contrast imaging (LSCI) could be used for such measurements, and to monitor perfusion during strabismus surgery on one or two horizontal rectus muscles.

Researchers state that this is the first ever study conducted to monitor perfusion during surgery in the anterior segment, with LSCI two muscles were easily deatched with a very little effect on the circulation in the anterior segment leading to lesser complications post operatively. The use of LSCI in strabismus surgery may allow for accurate and noninvasive monitoring of the anterior segment perfusion intraoperatively.

Researchers in a cohort evaluated Forty-four eyes in 44 patients with horizontal strabismus who underwent corrective surgery involving medial and/or lateral rectus muscle detachment. Perfusion in the adjacent paralimbal and iris tissue was monitored with LSCI.

The key findings of the study are

• When the first horizontal rectus muscle was detached perfusion in the adjacent paralimbal tissue decreased by 23% (p<0.0001), and by 12% (p<0.0001) when the second muscle was detached.

• The iris perfusion decreased by 5% (p<0.05) when the first muscle was detached but showed no significant decrease as the second muscle was cut.

Researchers concluded that “This is the first study showing that perfusion of the anterior segment can be monitored non-invasively with LSCI during strabismus surgery. In this cohort, two horizontal rectus muscles were detached with only a small decrease in the anterior segment circulation. Future studies are required for complete mapping of the effect of surgery on multiple ocular muscles on the anterior segment circulation.

Reference: Engqvist L, Sheikh R, Albinsson J, et al Laser speckle contrast imaging enables perfusion monitoring of the anterior segment during strabismus surgery: a study on the horizontal rectus muscles; British Journal of Ophthalmology 2023;107:1704-1708.